Benzothiazolone derivatives are known. For example, international patent applications, publication numbers WO92/08708 and WO93/23385 disclose biologically active amines, among them biologically active aminoethyl benzothiazolone derivatives which are .beta..sub.2 -adrenoreceptor agonists and dopamine DA.sub.2 -receptor agonists, and which are indicated in the treatment of obstructive airways diseases.
WO 93/24473 discloses 7-(2-aminoethyl)-benzothiazolone compounds of formula ##STR2## wherein X and Y are independently --S(O).sub.n -- or --O--; n is 0,1 or 2; p, q and r are independently 2 or 3; Z is phenyl optionally substituted by halogen, OR.sup.1, NO.sub.2 or NR.sup.2 R.sup.3 ; or Z is a 5 or 6 membered N, O or S containing heterocycle; and R.sup.1, R.sup.2 and R.sup.3 are independently hydrogen or alkyl C.sub.1-6. The compounds are .beta..sub.2 -adrenoreceptor agonists and dopamine DA.sub.2 -receptor agonists, and are indicated in the treatment of obstructive airways diseases.
We have now found a group of novel 7-(2-aminoethyl)-benzothiazolone derivatives which are useful as dopamine DA.sub.2 -receptor agonists and .beta..sub.2 -adrenoreceptor agonists.
Outline of the Invention
Accordingly, in one aspect of the present invention there are provided compounds of formula I including optical isomers thereof, ##STR3## wherein X represents --SO.sub.2 NH-- or --NHSO.sub.2 --,
p, q and r independently represent 2 or 3, PA1 Y represents thienyl optionally substituted by alkyl or halogen, or phenylthio- or phenyl optionally substituted by alkyl or halogen, and each R independently represents H or alkyl and pharmaceutically acceptable salts, esters and amides thereof.
The compounds are pharmacologically active. They show both dopamine DA.sub.2 -receptor agonism and .beta..sub.2 -adrenoreceptor agonism. They exhibit little or no .alpha..sub.1 -adrenoreceptor agonism. The compounds have an advantageous duration of action and DA.sub.2 /B.sub.2 ratio.
Preferably, q in formula I above is 2. r is preferably 2.
When Y is phenyl substituted by alkyl, the alkyl group is preferably a C.sub.1-6, for example a C.sub.1 or C.sub.2 group, most preferably methyl.
When Y is phenyl substituted by halogen, the halogen substituent is preferably a chloro- or fluoro-substituent.
Preferred compounds of the present invention are compounds of formula I wherein X is SO.sub.2 NH, p is 3 and q and r are each 2. Other preferred compounds are compounds of formula I wherein X is NHSO.sub.2, and p, q and r are all 2.
Suitable pharmaceutically acceptable salts of the compounds of formula I include acid addition salts derived from inorganic and organic acids. The compounds may also form salts with suitable bases. Examples of suitable salts include the hydrochloride, citrate, D,L-lactate, hemisulphate, hemitatrate, D-gluconate, methanesulphonate, p-toluenesulphonate, hemifurnarate, benzoate, xinafoate, hemisuccinate, 3-hydroxy-2-naphthoate, hemiembonate, hemimaleate, D-camphorsulphonate, 10-undecanoate, mandelate, naphthalene-1-sulphonate, naphthalene-2-sulphonate, 4-methoxybenzoate, 4-chlorobenzoate, 5-methylsalicylate, saccharinate, monomethyl suberate, hemisuberate and diphenyl acetate salts.
Suitable pharmaceutically acceptable esters of the compounds of formula I include phenylalkyl and alkyl esters.
Suitable amides include unsubstituted or mono- or di-substituted alkyl or phenyl amides.
The most preferred compounds of the invention are
3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-(2-phenylet hoxy)ethyl]propanesulphonamide; PA0 N-[2-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]ethyl]-2-(2- phenylethoxy)ethanesulphonamide; PA0 3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-[2-(5-methy l-2-thienyl)ethoxy]ethyl]propanesulphonamide; PA0 N-[2-[2-(4-Fluorophenyl)ethoxy]ethyl]-3-[2-(4-hydroxy-2-oxo-3H-1,3-benzothi azol-7-yl)ethylamino] propanesulphonamide; PA0 N-[2-[2-(4-Chlorophenyl)ethoxy]ethyl]-3-[2-(4-hydroxy-2-oxo-3H-1,3-benzothi azol-7-yl)ethylamino]propanesulphonamide; PA0 3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-[2-(4-methy lphenyl)ethoxy]ethyl]propanesulphonamide; PA0 (R,S)-3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-(2-ph enyl-1-propoxy)ethyl]propanesulphonamide; PA0 3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-[2-(2-methy lphenyl)ethoxy]ethyl]propanesulphonamide; and PA0 3-[2-(4-Hydroxy-2-oxo-3H-1,3-benzothiazol-7-yl)ethylamino]-N-[2-(2-phenylth ioethoxy)ethyl]propanesulphonamide;
preferably in salt form and more preferably as the hydrochloride.
The present invention also provides a method for the production of compounds of formula I, comprising selective reductive alkylation of a compound of formula II, ##STR4## with a compound of formula III, ##STR5## in which p, q, r, R, X and Y are as defined above, in the presence of a reducing agent.
The reducing agent may be, for example, hydrogen in the presence of a catalyst such as platinum, platinum oxide, palladium, palladium oxide, Raney nickel or rhodium, on a support e.g. charcoal, using an alcohol, e.g. ethanol, or an ester, e.g. ethyl acetate, or an ether, e.g. tetrahydrofuran, or water, as reaction solvent, or a mixture of solvents, at normal or elevated temperature and pressure. The preferred temperature is room temperature. The preferred pressure is 1-3atmospheres. Alternatively the reducing agent may be sodium borohydride or a metal hydride e.g. sodium cyanoborohydride. Suitable solvents for use with hydride reducing agents will depend on the particular hydride used and will be well known to the person skilled in the art. Suitable solvents will include alcohols, for example ethanol or methanol.
The process may give rise to intermediate imine compounds, which may be reduced under the described conditions, to give compounds of formula I.
The compound of formula II may be prepared by known methods, for example by the method described in J. Med. Chem., 1987, 30, 1116.
Aldehydes of formula III may be prepared in a number of ways known per se. For example, isothiazolidine dioxides (as in Example 1c, for instance) may be reduced with DIBAL in toluene; acetals (as in Example 2b, for instance) may be hydrolysed with 70% aqueous acetic acid; and esters (as in Example 3d, for instance) may be reduced with DIBAL in toluene. Specific syntheses of certain precursor compounds are described in the Examples and may be adapted to a variety of targets.
The aldehydes of formula III may also be prepared from the corresponding alcohols by partial oxidation using DMSO, DCC and anhydrous phosphoric acid; or using pyridinium chlorochromate or pyridinium dichromate.
The present invention also provides a further process for preparing compounds of formula I, comprising the selective reduction of a compound of formula IV, ##STR6## in which p, q, r, R, X and Y are as defined above.
Suitable reducing agents include electrophilic reducing agents, e.g., diborane and alane (aluminium hydride), or nucleophilic reducing agents, e.g., a complex metal hydride such as sodium bis(2-methoxyethoxy)aluminium hydride. The preferred reducing agent is diborane. The solvent should be inert to the reaction conditions. Aprotic solvents are preferred, e.g. tetrahydrofuran, diethyl ether, or 1,2-dimethoxyethane. The reaction may be carried out at a temperature of from about 0.degree. C., to about 100.degree. C., preferably at reflux temperature.
Compounds of formula IV may be prepared by coupling of the amine of formula II and an appropriate acid, of formula V ##STR7## or corresponding acid chloride by conventional means. For example, the coupling may be performed in the presence of dicyclohexylcarbodiimide using the method of Sheehan and Hess, J. Am. Chem. Soc., 1955, 77, 1067; or 1,1'-carbonyldiimidazole as described by Staab, Angew. Chem. Int. Ed. Engl., 1962, 1, 351; or bromotripyrrolidinophosphonium hexafluorophosphate in a solvent such as DMF, following the procedure of Example 1e. The acids required for the process may be obtained from the corresponding esters, by hydrolysis with lithium hydroxide in aqueous methanol, following the procedure of Example 1b. Examples 1a, 2d, 3d, 4f, 5d, 6d, 7d, 8d and 9d describe specific processes for forming is the esters, and these process may be adapted to give other esters, for forming further acids for coupling with formula II amines. The acid chlorides may be prepared from the acids for example by reaction with oxalyl chloride or thionyl chloride in toluene at a temperature from ambient to reflux.
The compounds of the present invention may be prepared by several other methods as well.
Alkylation of the compound of formula II, or a salt, ester or amide thereof, with an alkylating agent of formula VI ##STR8## in which p, q, r, R, X and Y are as defined above and L represents a good leaving group, for example a halide e.g. chloride, bromide or iodide, or an alkyl- or aryl-sulphonyloxy group, for example methanesulphonyloxy, is one such method.
The reaction may be carried out for example in the presence of a base, for example an inorganic base, e.g., sodium or potassium carbonate, or an organic base, e.g., triethylamine, N,N'-diisopropylethylamine or pyridine.
The reaction may be performed in a solvent, for example an ether, e.g. tetrahydrofuran or dioxan, a ketone, e.g. butanone or methyl isobutyl ketone, a substituted amide, e.g. dimethylformamide, or a chlorinated hydrocarbon, e.g. chloroform, at a temperature of between ambient temperature and the reflux temperature of the solvent. Preferably the reaction is carried out at ambient temperature.
The alkylating agent of formula VI may be prepared from the corresponding alcohol (i.e. the compound in which L represents OH) by methods known to the person skilled in the art. For example, the alcohol may be reacted with a halogenating agent to yield the compound of formula VI in which L represents a halogen atom. Suitable halogenating agents include, for example, triphenylphosphine-tetrahalogenomethane adduct (conveniently formed in situ, e.g. by the reaction of triphenylphosphine and carbontetrabromide). The reaction may take place in the presence of a solvent such as acetonitrile, or a chlorinated hydrocarbon, e.g. dichloromethane, for example at a temperature in the range of 0-30.degree. C.
Another method is the selective reduction of a compound of formula VII, ##STR9## in which p, q, r, R, X and Y are as defined above.
Suitable reducing agents include electrophilic reducing agents, e.g., diborane and alane (aluminium hydride), or nucleophilic, e.g., a complex metal hydride such as sodium bis(2-methoxyethoxy)aluminium hydride. The preferred reducing agent is diborane. The solvent should be inert to the reaction conditions. Aprotic solvents are preferred, e.g. tetrahydrofuran, diethyl ether, or 1,2-dimethoxyethane. The reaction may be carried out at a temperature of from about 0.degree. C., to about 100.degree. C., preferably at reflux temperature.
Compounds of formula VII may be prepared by coupling of an amine and an acid or acid chloride by conventional means. For example, the coupling may be performed in the presence of dicyclohexylcarbodiimide or 1,1'-carbonyldiimidazole or bromotripyrrolidinophosphonium hexafluorophosphate, as described above in relation to compounds of formula IV. The amines required for the coupling reaction may be prepared by reaction of compounds of formula VI, where L represents a good leaving group for example a halide such as chloride or bromide, with phthalimide in the presence of a base. The resulting imides may then be treated with hydrazine hydrate in ethanol to give compounds of formula VI with the leaving group replaced by an amino group.
In the above processes it may be necessary for any functional groups. e.g. hydroxy or amino groups, present in the starting materials to be protected. Suitable protecting groups and methods for their removal are, for example, those described in "Protective Groups in Organic Synthesis" by T. W. Greene and P. G. M. Wuts, John Wiley and Sons Inc., 1991.
Another process for preparing compounds of formula I comprises removal of a protecting group from a corresponding protected compound of formula I in which one or more of the functional groups is protected, and where desired or necessary converting the resulting compound of formula I to a pharmaceutically acceptable salt, ester or amide thereof or vice versa.
Pharmaceutically acceptable salts may be prepared for example by reacting the compound of formula I with an appropriate acid in the presence of a suitable solvent. Pharmaceutically acceptable esters of the compounds of formula I may be made by conventional techniques, e.g. esterification or transesterification.
Pharmaceutically acceptable amides of the compounds of formula I may be made by conventional techniques, e.g. reaction of a compound of formula I with an acid or acid chloride.
The intermediates of formula IV are novel, thus according to a further aspect of the invention there are provided compounds of formula IV, ##STR10## in which p, q, r, R, X and Y are as defined above.
The intermediates of formula VII as defined above are also novel and are thus also provided in accordance with the present invention.
Further, the aldehydes of formula III as defined above are novel and are provided by the present invention.
Still further the acids of formula V and corresponding acid chlorides are novel and are provided by the present invention.
The compounds of formula I and salts, esters and amides thereof are dopamine DA.sub.2 -receptor agonists. The binding affinities of the test compounds for the DA.sub.2 receptor binding sites in bovine pituitary membranes may be determined from the displacement of [.sup.3 H]-N-n -propylnorapomorphine and of [.sup.3 H]-spiperone in the absence or presence of nonhydrolysable GTP analogue respectively, D. R. Sibley, A. DeLean and I. Creese, Anterior Pituitary Dopamine Receptors, Demonstration of Interconvertible High and Low Affinity States of the D-2 Dopamine Receptor, J. Biol. Chem, 1982, 257(11), 6351-6361. The DA.sub.2 -receptor activity may also be demonstrated in a functional screen, the rabbit isolated ear artery, as described by Brown and O'Connor, Br. J. Pharmacol., 1981, 73, 189P. The compounds are also .beta..sub.2 -adrenoreceptor agonists. This activity may be demonstrated in the isolated trachea of the guinea pig, as described by I. G. Dougall, D. Harper, D. M. Jackson, and P. Leff, Br. J. Pharmacol., 1991, 104, 1057. .alpha..sub.1 -Receptor activity may be analysed using the rabbit isolated ear artery screen described in Pharmacological Example herein.
The compounds of formula I and salts, esters and amides thereof are thus indicated for use in the treatment of the range of airways diseases, including conditions such as asthma, including bronchial asthma, allergic asthma, intrinsic asthma (for example late asthma and airway hyper-responsiveness); and bronchitis and the like (see, for example, UK Patent No. 2022078 and Br. J. Pharmacol., 1987, 24, 4983).
The compounds of formula I and salts, esters and amides thereof are also indicated for use in the treatment of various other conditions, e.g. inflammatory and allergic skin disorders, cancer e.g. small cell lung cancer, congestive heart failure and glaucoma.
The term "treatment" as used herein includes prophylaxis as well as relief of the symptoms of disease.
Accordingly, in a further aspect of the present invention, there is provided the use of a compound of formula I, or a pharmaceutically acceptable salt, ester or amide thereof in therapy.
Further, there is provided the use of a compound of formula I, or a pharmaceutically acceptable salt, ester or amide thereof, in the manufacture of a medicament for the treatment of obstructive airways disease, in particular for the treatment of asthma or chronic bronchitis.
Still further, the present invention provides a method of treatment of airways disease, which method comprises administering a therapeutically effective quantity of a compound of formula I, or a pharmaceutically acceptable salt, ester or amide thereof, to a patient suffering from or susceptible to such a condition.
Typical daily unit doses may be for example 1 .mu.g-10 mg for topical administration, preferably 10-500 .mu.g, for example divided two or three times, or 10 .mu.g-100 mg for oral administration, preferably 100 .mu.g-10 mg, for example divided two or three times.
The compounds of formula I and salts, esters and amides thereof may be used on their own or in the form of appropriate pharmaceutical compositions.
Administration may be by inhalation as well as by other routes, for example by oral or intraveneous administration.
Nasal or pulmonary administration may be achieved via a suitable inhalation device.
For example metered dose inhaler devices may be used to administer the compound, dispersed in a suitable propellant and with or without additional excipients such as ethanol, surfactants, lubricants and stabilising agents.
Suitable propellants include hydrocarbon, chlorofluorocarbon and hydrofluoroalkane propellants, or mixtures of any such propellants. Especially preferred propellants are P134a and P227 each of which may be used alone or in combination with other propellants and/or surfactants and/or other excipients, for example in combination with each other.
Nebulised aqueous suspensions or, preferably, solutions may also be employed, with or without a suitable pH and/or tonicity adjustment, either as a unit-dose or multi-dose device.
Dry powder inhalers may be used to administer the compound, alone or in combination with a pharmaceutically acceptable carrier, in the latter case either as a finely divided powder or as an ordered mixture. The dry powder inhaler may be single dose or multi-dose and may utilise a dry powder or a powder-containing capsule.
Metered dose inhaler, nebuliser and dry powder inhaler devices are well known and a variety of such devices are available.
The invention is illustrated, but in no way limited, by the following Examples, in which temperatures are in degrees Celsius. Where necessary, the reactions were performed under an inert atmosphere of either nitrogen or argon. Where necessary, preparative HPLC separations were generally performed using a Novapak.RTM., Bondapak.RTM. or Hypersil.RTM. column packed with BDSC-18 reverse phase silica. Flash chromatography was carried out using Fisher Matrix 60 silica, 35-70 micron.